Final answer:
Heat is transferred through the copper rod by conduction, a process where thermal energy is transferred through matter by the physical contact and movement of atoms and molecules.
Step-by-step explanation:
When small pieces of wax placed along a copper rod melt at progressively larger distances from the flame of a Bunsen burner, this is an example of heat transfer through the rod by conduction. Conduction is the process of heat transfer through stationary matter by physical contact; the matter is stationary on a macroscopic scale, but there is still thermal motion of atoms and molecules. In metals like copper, which are good electrical conductors, thermal energy is efficiently transferred because the free electrons in the metal aid in the transfer of energy between atoms.
As the copper rod is heated at one end, the molecules at that end increase in kinetic energy and collide with adjacent, cooler molecules, transferring energy in the process and causing the wax to melt progressively further from the heat source.